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7.11.4.1. Set Point Control Option
Set point control mode is commonly used in areas with high occupancy and frequent change out such as classrooms or
conference rooms.
In applications requiring this on/off damper response to carbon dioxide levels, set the start open (Parameter 118 - DCV
DAMP START OPEN) set point higher than the full open (Parameter 119 - DCV DAMP FULL OPEN) set point. The dampers
will drive to fully-open position immediately. Figure 11 shows the set point control option.
Change Parameters 122 and 123 to set the minimum outdoor temperature limits. Change Parameters 120 and 121 to set
the maximum temperature limits.
IMPORTANT
Mixed air temperatures less than 45°F (7°C) on units with an aluminized heat exchanger or less than 30°F (-1°C) on
stainless steel heat exchangers will void the manufacturer's warranty.
Min. Position
100
Parameter 117
Parameter 119
(full)
Parameter 118
(start)
carbon dioxide (ppm)
Max. Open
Close Open
Figure 11. Set point Control Indoor Air Quality Option
7.11.4.2. Determining Indoor Air Quality Inputs
Go to DATA> IN/OUTPUTS > SENSORS menu selection from the M3 Unit Controller menu display.
8. Power Exhaust Operation
The M3 Controller is capable of controlling up to two stages of power exhaust. The M3 configuration has to match the power
exhaust equipment installed in the roof top unit:
Configuration ID 1 position 3 needs to be set to one of the following options::
N No power exhaust installed
S Single stage power exhaust
D Dual stage power exhaust.
To enable power exhaust control Configuration ID 1 position 4 needs to be set to A for enabling damper position control.
See table 33 for further details.
Table 33. Exhaust Control
Single-Stage Exhaust Set Points (SP) Dead-band (DB)
Enabled when Input Parameter Default Parameter Default
Blower is energized. Fresh Air Damper Position 215 50% Travel 216 20% Travel*
A55_P265-12 output energizes the first stage exhaust relay when the fresh air damper position reaches 50% Travel (Parameter 215) when the
blower is operating. The exhaust will de-energize when the damper position decreases 20% (Parameter 216) less than the set point or when the
blower is de-energized.
Two-Stage Exhaust Set points (SP) Dead-band (DB)
Enabled when Input Parameter Default Parameter Default
Blower is energized. Fresh Air Damper Position
215 50% Travel 216 20% Travel*
219 70% Travel 220 10% Travel
* Indicates to check unit parameter label as default may be altered at factory test.
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